Recently, the number of people who continuously have their hair colored has increased. Under such circumstances, coloring to obtain uniform color over the entire hair or coloring to change the hair to a different color is frequently requested, particularly as the hair grows.
When coloring for obtaining uniform color or coloring for changing the hair to different color is performed, coexistence of original hair having been not colored (referred to as “virgin hair” hereinafter) and hair having been already colored (referred to as “already-colored hair” hereinafter) has to be taken into consideration.
For example, in case of hair having been colored with a general oxidative hair-coloring agent, melanin has been destroyed and the dye has been gradually washed away to discolor the hair in the already-colored hair portions, and these portions have higher lightness as compared with the virgin hair portions. Therefore, even if the same hair-coloring agent is used, the already-colored hair portions exhibit color tone of higher lightness as compared with the virgin hair portions, resulting in a problem that uniform coloring over the whole hair is impossible.
Under such circumstances as mentioned above, the present inventors have earnestly studied, and as a result, they have found that uniform color tone can be realized over the whole hair by the use of different hair-coloring agents, namely, oxidative hair-coloring agents each of which contains ammonia and hydrogen peroxide in specific concentrations, for the virgin hair portions and the already-colored hair portions. Based on the finding, the present invention has been accomplished.
Accordingly, it is an object of the present invention to provide a hair-coloring method by which hair having virgin hair portions and already-colored hair portions can be colored in uniform color tone over the whole hair, and a hair-coloring agent set which is favorably used for the hair-coloring method.